Salvinorin B methoxymethyl ether (2-O-methoxymethylsalvinorin B, or 2-MMSB) is a semi-synthetic analogue of the natural product Salvinorin A which is used in scientific research. It has a longer duration of action of around 2–3 hours, compared to less than 30 minutes for salvinorin A, and has increased affinity and potency at the κ-opioid receptor. Like the related compound herkinorin, salvinorin B methoxymethyl ether is made from salvinorin B, which is most conveniently made from salvinorin A by deacetylation, as while both salvinorin A and salvinorin B are found in the plant Salvia divinorum, salvinorin A is present in larger quantities.

Salvinorin B methoxymethyl ether has a Ki of 0.60 nM at the κ opioid receptor, and is around five times more potent than salvinorin A in animal studies, although it is still only half as potent as its stronger homolog salvinorin B ethoxymethyl ether.